<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script>
			// forEach的使用,index参数可以省略
			let arr = [12,5,8,11];
			let result = arr.forEach((item,index)=>{
				alert(index + ":"+item)
			});
			// console.log(result);
		</script>
	</head>
	<body>
	</body>
</html>
